The total area of facility cultivation in Korea is 54,218ha as of 2016, and most types of these are greenhouses. Proper ventilation inside has a great influence on the productivity of crops. In this study, we compared the ventilation and summer temperature control performances of the conventional vinyl greenhouses and the triangular high - rise vinyl greenhouses. We analyzed the effect of ventilation conditions on the internal temperature of the plastic house by simulation. In particular, we tried to analyze quantitatively the effect of improvement of the thermal environment inside the vinyl house during the summer by improving the ventilation system. We analyzed the ventilation conditions depending on the type of vinyl house in three types and analyzed the effect of the three ventilation methods on the temperature change of the vinyl house by simulation. The results can be summarized as follows. When both the sides of the vinyl house and the openings of the upper part were opened, the temperature change of the general vinyl house and the triangular high-ventilated greenhouse was not statistically different.